"At the end of 2014, the United States and partner countries completed a transition to a smaller mission consisting primarily of training and advising the Afghanistan National Security Forces (ANSF). The number of U.S. forces in Afghanistan, which peaked at about 100,000 in June 2011, stands at about 9,800. About 1,000 of the U.S. contingent are counter-terrorism forces that continue to conduct combat, operating under U.S. 'Operation Freedom's Sentinel' that has replaced the post-September 11 'Operation Enduring Freedom.' U.S. forces constitute the bulk of the 13,000-person NATO-led 'Resolute Support Mission.' The post-2016 U.S. force is to be several hundred military personnel, under U.S. Embassy authority. However, amid assessments that the ANSF is having some difficulty preventing gains by the Taliban and other militant groups, President Obama announced that U.S. forces would remain at about 10,000 through the end of 2015. There has not been an announced change in the size in the post-2016 U.S. forces. U.S. officials assert that insurgents do not pose a threat to the stability of the government, but militants continue to conduct high-profile attacks and gain ground in some areas. The insurgency benefits, in some measure, from weak governance in Afghanistan."
CRS Report for Congress, RL30588
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html